An international research team, led by the British Antarctic Survey (BAS), is investigating how glacier calving in Antarctica generates powerful underwater tsunamis.
Discovery and Impact
When icebergs detach from glaciers and enter the ocean, this process, known as calving, creates strong underwater tsunamis. These submerged waves, often several meters high, cause significant ocean mixing. This mixing churns heat, oxygen, and nutrients across different water depths, which is vital for marine life and regional climate regulation.
Previously, ocean mixing was primarily attributed to wind, tides, and surface heat loss. However, initial findings suggest that underwater tsunamis play a substantial role in polar oceans. Their effect is comparable to wind-driven mixing in certain areas and has a greater impact than tides in redistributing ocean heat.
This phenomenon was first observed by chance during a previous BAS expedition to Antarctica aboard the RRS James Clark Ross, led by Professor James Scourse from the University of Exeter. Ocean data was collected before, during, and after a calving event.
Current Research Efforts
Scientists are now at Rothera Research Station on the Antarctic Peninsula and on the UK's polar research ship RRS Sir David Attenborough to conduct further studies on underwater tsunamis.
Professor Michael Meredith, an oceanographer at BAS and lead researcher, aims to understand the creation, function, and impact of these tsunamis. This includes investigating how different types of calving and seasonal conditions affect tsunami formation and how the resulting mixing influences polar climate and ecosystems.
Professor Katy Sheen, an oceanographer at Exeter and co-lead for part of the project, is focusing on the link between glacial calving and internal tsunami generation. The field work involves collecting observations to characterize both calving events and the tsunamis they cause. Remote cameras and underwater microphones monitor calving, while unmanned underwater vehicles, moored instruments, and water sampling measure generated tsunamis and their effects on local chemistry and biology.
Dr. Alexander Brearley, a BAS oceanographer, is currently using an autonomous underwater vehicle at Rothera Research Station to study the Sheldon Glacier. The team is deploying advanced air, land-based, and ocean technologies to document individual glacier calving events and their tsunami impacts with high resolution.
Broader Implications
Underwater tsunamis and the mixing they induce could have significant consequences for the Southern Ocean and globally. Increased ocean mixing may draw warmer water from deeper layers, potentially accelerating the melting of the Antarctic Ice Sheet and contributing to global sea level rise. This mixing can also alter nutrient distribution, impacting phytoplankton growth, which forms the base of the ocean food chain.
Professor Kate Hendry, a chemical oceanographer at BAS, emphasizes the interconnectedness of Antarctica's ice, ocean, and atmosphere, and how these processes influence global phenomena such as sea levels and weather patterns.
Future research will address whether the warming climate might increase the frequency and intensity of calving and tsunami events. Understanding this phenomenon will enhance ocean models used for climate change predictions.
Collaboration
The POLOMINTS project is a collaboration led by the British Antarctic Survey, involving the Scottish Association for Marine Science, the University of Southampton, the University of Leeds, the National Oceanography Centre, the University of Exeter, Bangor University, and international partners from the Scripps Institution of Oceanography (USA), the Institute of Geophysics of the Polish Academy of Sciences (Poland), the University of Delaware (USA), and Rutgers University (USA).